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<p>Incineration bottom ash (IBA) and fly ash contain toxic heavy metals that can be immobilized using a bio-solidification method. Urease-producing bacteria (UPB) can hydrolyze urea and produce carbonate ions that interact with heavy metal ions to form water-insoluble carbonates. The activity of UPB can maintain a urease activity of 5 U within 63&#xa0;days in a UPB solution. This method can effectively remove heavy metals (HMs), such as high concentrations of copper ions, from IBA solutions. In each liter of copper ion solution, the optimal conditions for removal are a mass ratio of urea to UPB of 1:333, a standing time of 24&#xa0;h, and a molar ratio of urea to heavy metal ions of 1:1. The removal efficiency of copper ions with different concentrations is between 71 to 79%. Biominerals formed through this process are characterized by X-ray diffraction analysis (XRD), energy dispersive X-ray spectroscopy (EDS), fourier transform infrared spectrometer (FTIR), and thermogravimetric analysis and differential scanning calorimetry (TGA–DSC). The results show that the precipitate is bio-CuCO<sub>3</sub>. Microscopy observation using scanning transmission electron microscopy (STEM) reveals an irregular flaky structure with a size in the range of 150&#xa0;μm. This study demonstrates that using the best formula, copper ions eluted from IBA can be removed within 24&#xa0;h with a removal efficiency of over 95%. The method is also effective for low-concentration lead ions in IBA. The bio-solidification method can be effectively applied to stabilize and immobilize high concentrations of heavy metal ions present in soil and wastewater.</p> Graphical Abstract <p>Highlights</p> <p>1. The urease activity can be maintained at 20 U within 7&#xa0;days.</p> <p>2. The bio-solidification method can remove a high concentration of copper ions.</p> <p>3. The best formula for the bio-carbonate cement by various influencing factors.</p> <p>4. The chemical composition and microstructure of the biominerals are analyzed.</p> <p>5. The mechanisms of urea hydrolysis and cation mineralization are discussed in detail.</p> <p></p>

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Immobilization of Heavy Metals in Incineration Bottom Ash using Bio-solidification Method

  • 期刊论文

  • 发表日期：

    2025年12月18日

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  • Xiaoniu Yu,
  • Ye Qian,
  • Yan Sun,
  • Guoqiang Du

摘要

Incineration bottom ash (IBA) and fly ash contain toxic heavy metals that can be immobilized using a bio-solidification method. Urease-producing bacteria (UPB) can hydrolyze urea and produce carbonate ions that interact with heavy metal ions to form water-insoluble carbonates. The activity of UPB can maintain a urease activity of 5 U within 63 days in a UPB solution. This method can effectively remove heavy metals (HMs), such as high concentrations of copper ions, from IBA solutions. In each liter of copper ion solution, the optimal conditions for removal are a mass ratio of urea to UPB of 1:333, a standing time of 24 h, and a molar ratio of urea to heavy metal ions of 1:1. The removal efficiency of copper ions with different concentrations is between 71 to 79%. Biominerals formed through this process are characterized by X-ray diffraction analysis (XRD), energy dispersive X-ray spectroscopy (EDS), fourier transform infrared spectrometer (FTIR), and thermogravimetric analysis and differential scanning calorimetry (TGA–DSC). The results show that the precipitate is bio-CuCO3. Microscopy observation using scanning transmission electron microscopy (STEM) reveals an irregular flaky structure with a size in the range of 150 μm. This study demonstrates that using the best formula, copper ions eluted from IBA can be removed within 24 h with a removal efficiency of over 95%. The method is also effective for low-concentration lead ions in IBA. The bio-solidification method can be effectively applied to stabilize and immobilize high concentrations of heavy metal ions present in soil and wastewater.

Graphical Abstract

Highlights

1. The urease activity can be maintained at 20 U within 7 days.

2. The bio-solidification method can remove a high concentration of copper ions.

3. The best formula for the bio-carbonate cement by various influencing factors.

4. The chemical composition and microstructure of the biominerals are analyzed.

5. The mechanisms of urea hydrolysis and cation mineralization are discussed in detail.